Sounding for radio-frequency (rf) sensing

ABSTRACT

This disclosure provides methods, devices and systems for radio frequency (RF) sensing in wireless communication systems. In some implementations, a transmitting device may transmit a sounding dataset, over a wireless channel, to a receiving device. The sounding dataset may include information carried in one or more training fields configured for channel estimation and sounding control information based, at least in part, on a configuration of the transmitting device. The receiving device may acquire channel state information (CSI) for the wireless channel based on the received sounding dataset and selectively generate a channel report for the wireless channel based, at least in part, on the CSI and the sounding control information. The channel report may indicate changes to the wireless channel which, in turn, may be used to sense objects in the vicinity of the transmitting device or the receiving device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Patent Application claims priority to U.S. Provisional PatentApplication No. 62/970,857 entitled “SOUNDING FOR RADIO-FREQUENCY (RF)SENSING” and filed on Feb. 6, 2020, which is assigned to the assigneehereof. The disclosure of the prior Application is considered part ofand are incorporated by reference in this Patent Application.

TECHNICAL FIELD

This disclosure relates generally to wireless communication, and morespecifically, to sounding techniques for RF sensing in wirelesscommunication systems.

DESCRIPTION OF THE RELATED TECHNOLOGY

Wireless communication devices communicate by transmitting and receivingelectromagnetic signals in the radio frequency (RF) spectrum. Theoperating environment of the wireless communication devices affects thepropagation of the electromagnetic signals. For example, electromagneticsignals transmitted by a transmitting device may reflect off objects andsurfaces in the environment before reaching a receiving device located adistance away. Accordingly, the amplitudes or phases of theelectromagnetic signals received by the receiving device may depend, atleast in part, on the characteristics of the environment.

RF sensing is a technique for sensing objects or movement in anenvironment based, at least in part, on the transmission and receptionof electromagnetic signals. More specifically, changes in theenvironment can be detected based on changes in the electromagneticsignals (such as phase or amplitude) propagating through theenvironment. For example, a person moving through the environmentinterferes with the electromagnetic signals that are transmitted by atransmitting device. A receiving device may detect and characterize suchchanges to its received signals to determine the speed or direction ofthe person's movement.

The range of applications or accuracy of RF sensing may depend on theamount or detail of information communicated between the transmittingdevice and the receiving device. Accordingly, a mechanism is needed tofacilitate the exchange of information between the transmitting deviceand the receiving device when performing RF sensing.

SUMMARY

The systems, methods and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

One innovative aspect of the subject matter described in this disclosurecan be implemented as a method of wireless communication. The method maybe performed by a wireless communication device, and may includereceiving a sounding dataset, over a wireless channel, from atransmitting device, where the sounding dataset includes informationcarried in one or more training fields configured for channel estimationand sounding control information indicating a configuration of thetransmitting device; acquiring channel state information (CSI) for thewireless channel based on the received sounding dataset; and selectivelytransmitting a channel report to the transmitting device based at leastin part on the CSI and the sounding control information.

In some implementations, the sounding control information may include asequence number indicating the configuration of the transmitting device.In some implementations, the sounding control information may includetiming information or information indicating one or more transmissionparameters associated with a transmission of the sounding dataset by thetransmitting device. In some implementations, the channel report mayinclude a subset of the sounding control information.

In some implementations, the channel report may include a sequencenumber indicating a configuration of the wireless communication device.In some implementations, the channel report may include timinginformation or information indicating one or more reception parametersassociated with the reception of the sounding dataset. In someimplementations, the selective transmitting of a channel report mayinclude obtaining an indication that a received signal strengthindication (RSSI) associated with the sounding dataset is below an RSSIthreshold, where no channel report is transmitted to the transmittingdevice based on the indication that the RSSI is below the RSSIthreshold.

In some implementations, the method may further include acquiring CSIfor a reference channel; and obtaining an indication of a differencebetween the CSI for the wireless channel and the CSI for the referencechannel. In some implementations, the channel report may include theindication of the difference in CSI. In some implementations, theselective transmitting of a channel report may include comparing thedifference in CSI to a CSI difference threshold, where no channel reportis transmitted to the transmitting device based on the difference in CSIbeing below the CSI difference threshold.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a wireless communication device. Insome implementations, the wireless communication device may include atleast one modem, at least one processor communicatively coupled with theat least one modem, and at least one memory communicatively coupled withthe at least one processor and storing processor-readable code. In someimplementations, execution of the processor-readable code by the atleast one processor causes the wireless communication device to performoperations including receiving a sounding dataset, over a wirelesschannel, from a transmitting device, the sounding dataset includinginformation carried in one or more training fields configured forchannel estimation and sounding control information indicating aconfiguration of the transmitting device; acquiring CSI for the wirelesschannel based on the received sounding dataset; and selectivelytransmitting a channel report to the transmitting device based at leastin part on the CSI and the sounding control information.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a method of wireless communication. Themethod may be performed by a wireless communication device, and mayinclude generating sounding control information based, at least in part,on a configuration of the wireless communication device; andtransmitting a sounding dataset, over a wireless channel, to a receivingdevice, where the sounding dataset includes the sounding controlinformation and information carried in one or more training fieldsconfigured for channel estimation.

In some implementations, the sounding control information may include asequence number indicating the configuration of the wirelesscommunication device. In some implementations, the sounding controlinformation may include timing information or one or more transmissionparameters associated with the transmission of the sounding dataset.

In some implementations, the method may further include receiving achannel report from the receiving device responsive to the transmissionof the sounding dataset, where the channel report includes CSI for thewireless channel; and sensing objects in a vicinity of the wirelesscommunication device based on the received channel report. In someimplementations, the channel report may include a subset of the soundingcontrol information. In some implementations, the channel report mayinclude a sequence number indicating a configuration of the receivingdevice. In some implementations, the channel report may include timinginformation or information indicating one or more reception parametersassociated with a reception of the sounding dataset by the receivingdevice.

In some implementations, the channel report may indicate a difference inCSI between the wireless channel and a reference channel. In someimplementations, the sounding control information may identify thereference channel. In some other implementations, the sounding controlinformation may idetify the wireless channel as a reference channel forfuture channel reports.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a wireless communication device. Insome implementations, the wireless communication device may include atleast one modem, at least one processor communicatively coupled with theat least one modem, and at least one memory communicatively coupled withthe at least one processor and storing processor-readable code. In someimplementations, execution of the processor-readable code by the atleast one processor causes the wireless communication device to performoperations including generating sounding control information based, atleast in part, on a configuration of the wireless communication device;and transmitting a sounding dataset, over a wireless channel, to areceiving device, where the sounding dataset includes the soundingcontrol information and information carried in one or more trainingfields configured for channel estimation.

BRIEF DESCRIPTION OF THE DRAWINGS

Details of one or more implementations of the subject matter describedin this disclosure are set forth in the accompanying drawings and thedescription below.

Other features, aspects, and advantages will become apparent from thedescription, the drawings and the claims. Note that the relativedimensions of the following figures may not be drawn to scale.

FIG. 1 shows a pictorial diagram of an example wireless communicationnetwork.

FIG. 2 shows an example protocol data unit (PDU) usable forcommunications between an access point (AP) and each of a number ofstations (STAs).

FIG. 3A shows an example PDU usable for communications between an AP andeach of a number of STAs.

FIG. 3B shows another example PDU usable for communications between anAP and each of a number of STAs.

FIG. 4 shows an example physical layer convergence protocol (PLCP)protocol data unit (PPDU) usable for communications between an AP andeach of a number of STAs.

FIG. 5 shows a block diagram of an example wireless communicationdevice.

FIG. 6A shows a block diagram of an example AP.

FIG. 6B shows a block diagram of an example STA.

FIGS. 7A and 7B shows an example radio frequency (RF) sensing systemaccording to some implementations.

FIG. 8A shows an example sounding dataset usable for RF sensingaccording to some implementations.

FIG. 8B shows another example sounding dataset usable for RF sensingaccording to some implementations.

FIG. 8C shows another example sounding dataset usable for RF sensingaccording to some implementations.

FIG. 9 shows a timing diagram illustrating an example message exchangebetween a transmitting device and a receiving device in an RF sensingsystem according to some implementations.

FIG. 10A shows a flowchart illustrating an example process for wirelesscommunication that supports sounding for RF sensing according to someimplementations.

FIG. 10B shows a flowchart illustrating an example process for wirelesscommunication that supports sounding for RF sensing according to someimplementations.

FIG. 11A shows a flowchart illustrating an example process for wirelesscommunication that supports sounding for RF sensing according to someimplementations.

FIG. 11B shows a flowchart illustrating an example process for wirelesscommunication that supports sounding for RF sensing according to someimplementations.

FIG. 12 shows a block diagram of an example wireless communicationdevice for use in wireless communication that supports sounding for RFsensing according to some implementations.

FIG. 13 shows a block diagram of an example wireless communicationdevice for use in wireless communication that supports sounding for RFsensing according to some implementations.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

The following description is directed to certain implementations for thepurposes of describing innovative aspects of this disclosure. However, aperson having ordinary skill in the art will readily recognize that theteachings herein can be applied in a multitude of different ways. Thedescribed implementations can be implemented in any device, system ornetwork that is capable of transmitting and receiving radio frequency(RF) signals according to one or more of the Institute of Electrical andElectronics Engineers (IEEE) 802.11 standards, the IEEE 802.15standards, the Bluetooth® standards as defined by the Bluetooth SpecialInterest Group (SIG), or the Long Term Evolution (LTE), 3G, 4G or 5G(New Radio (NR)) standards promulgated by the 3rd Generation PartnershipProject (3GPP), among others. The described implementations can beimplemented in any device, system or network that is capable oftransmitting and receiving RF signals according to one or more of thefollowing technologies or techniques: code division multiple access(CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA(SC-FDMA), single-user (SU) multiple-input multiple-output (MIMO) andmulti-user (MU) MIMO. The described implementations also can beimplemented using other wireless communication protocols or RF signalssuitable for use in one or more of a wireless personal area network(WPAN), a wireless local area network (WLAN), a wireless wide areanetwork (WWAN), or an internet of things (IOT) network.

Various implementations relate generally to RF sensing in wirelesscommunication systems. Some implementations more specifically relate tousing signaling techniques and packet formats conforming to the IEEE802.11 family of standards for performing RF sensing by one or morecommunication devices. A WLAN may be formed by one or more access points(APs) that provide a shared wireless communication medium for use by anumber of client devices also referred to as stations (STAs). The basicbuilding block of a WLAN conforming to the IEEE 802.11 family ofstandards is a Basic Service Set (BSS), which is managed by an AP. EachBSS is identified by a Basic Service Set Identifier (BSSID) that isadvertised by the AP. Wireless communication devices (such as APs andSTAs) communicate by transmitting and receiving electromagnetic signalsin the RF spectrum. Electromagnetic signals transmitted by atransmitting device may reflect off objects and surfaces along thetransmission path before reaching a receiving device located a distanceaway. The electromagnetic signals also may carry information and datathat can be used by the receiving device to measure the wirelesschannel. Accordingly, signaling techniques conforming to the IEEE 802.11family of standards may be well-suited for RF sensing.

In some implementations, a wireless communication network conforming tothe IEEE 802.11 family of standards (such as a WLAN) may be used toimplement an RF sensing system. A transmitting device may transmit asounding dataset, over a wireless channel, to a receiving device. Thesounding dataset may include information carried in one or more trainingfields configured for channel estimation and sounding controlinformation based, at least in part, on a configuration of thetransmitting device. The receiving device may acquire channel stateinformation (CSI) for the wireless channel based on the receivedsounding dataset and selectively generate a channel report for thewireless channel based, at least in part, on the CSI and the soundingcontrol information. The channel report may indicate changes to thewireless channel which, in turn, may be used to sense objects in thevicinity of the transmitting device or the receiving device.

FIG. 1 shows a block diagram of an example wireless communicationnetwork 100. According to some aspects, the wireless communicationnetwork 100 can be an example of a wireless local area network (WLAN)such as a Wi-Fi network (and will hereinafter be referred to as WLAN100). For example, the WLAN 100 can be a network implementing at leastone of the IEEE 802.11 family of wireless communication protocolstandards (such as that defined by the IEEE 802.11-2016 specification oramendments thereof including, but not limited to, 802.11ah, 802.11ad,802.11ay, 802.11ax, 802.11az, 802.11ba and 802.11be). The WLAN 100 mayinclude numerous wireless communication devices such as an access point(AP) 102 and multiple stations (STAs) 104. While only one AP 102 isshown, the WLAN network 100 also can include multiple APs 102.

Each of the STAs 104 also may be referred to as a mobile station (MS), amobile device, a mobile handset, a wireless handset, an access terminal(AT), a user equipment (UE), a subscriber station (SS), or a subscriberunit, among other possibilities. The STAs 104 may represent variousdevices such as mobile phones, personal digital assistant (PDAs), otherhandheld devices, netbooks, notebook computers, tablet computers,laptops, display devices (for example, TVs, computer monitors,navigation systems, among others), music or other audio or stereodevices, remote control devices (“remotes”), printers, kitchen or otherhousehold appliances, key fobs (for example, for passive keyless entryand start (PKES) systems), among other possibilities.

A single AP 102 and an associated set of STAs 104 may be referred to asa basic service set (BSS), which is managed by the respective AP 102.FIG. 1 additionally shows an example coverage area 106 of the AP 102,which may represent a basic service area (BSA) of the WLAN 100. The BSSmay be identified to users by a service set identifier (SSID), as wellas to other devices by a basic service set identifier (BSSID), which maybe a medium access control (MAC) address of the AP 102. The AP 102periodically broadcasts beacon frames (“beacons”) including the BSSID toenable any STAs 104 within wireless range of the AP 102 to “associate”or re-associate with the AP 102 to establish a respective communicationlink 108 (hereinafter also referred to as a “Wi-Fi link”), or tomaintain a communication link 108, with the AP 102. For example, thebeacons can include an identification of a primary channel used by therespective AP 102 as well as a timing synchronization function forestablishing or maintaining timing synchronization with the AP 102. TheAP 102 may provide access to external networks to various STAs 104 inthe WLAN via respective communication links 108.

To establish a communication link 108 with an AP 102, each of the STAs104 is configured to perform passive or active scanning operations(“scans”) on frequency channels in one or more frequency bands (forexample, the 2.4 GHz, 5 GHz, 6 GHz or 60 GHz bands). To perform passivescanning, a STA 104 listens for beacons, which are transmitted byrespective APs 102 at a periodic time interval referred to as the targetbeacon transmission time (TBTT) (measured in time units (TUs) where oneTU may be equal to 1024 microseconds (μs)). To perform active scanning,a STA 104 generates and sequentially transmits probe requests on eachchannel to be scanned and listens for probe responses from APs 102. EachSTA 104 may be configured to identify or select an AP 102 with which toassociate based on the scanning information obtained through the passiveor active scans, and to perform authentication and associationoperations to establish a communication link 108 with the selected AP102. The AP 102 assigns an association identifier (AID) to the STA 104at the culmination of the association operations, which the AP 102 usesto track the STA 104.

As a result of the increasing ubiquity of wireless networks, a STA 104may have the opportunity to select one of many BSSs within range of theSTA or to select among multiple APs 102 that together form an extendedservice set (ESS) including multiple connected BSSs. An extended networkstation associated with the WLAN 100 may be connected to a wired orwireless distribution system that may allow multiple APs 102 to beconnected in such an ESS. As such, a STA 104 can be covered by more thanone AP 102 and can associate with different APs 102 at different timesfor different transmissions. Additionally, after association with an AP102, a STA 104 also may be configured to periodically scan itssurroundings to find a more suitable AP 102 with which to associate. Forexample, a STA 104 that is moving relative to its associated AP 102 mayperform a “roaming” scan to find another AP 102 having more desirablenetwork characteristics such as a greater received signal strengthindicator (RSSI) or a reduced traffic load.

In some cases, STAs 104 may form networks without APs 102 or otherequipment other than the STAs 104 themselves. One example of such anetwork is an ad hoc network (or wireless ad hoc network). Ad hocnetworks may alternatively be referred to as mesh networks orpeer-to-peer (P2P) networks. In some cases, ad hoc networks may beimplemented within a larger wireless network such as the WLAN 100. Insuch implementations, while the STAs 104 may be capable of communicatingwith each other through the AP 102 using communication links 108, STAs104 also can communicate directly with each other via direct wirelesslinks 110. Additionally, two STAs 104 may communicate via a directcommunication link 110 regardless of whether both STAs 104 areassociated with and served by the same AP 102. In such an ad hoc system,one or more of the STAs 104 may assume the role filled by the AP 102 ina BSS. Such a STA 104 may be referred to as a group owner (GO) and maycoordinate transmissions within the ad hoc network. Examples of directwireless links 110 include Wi-Fi Direct connections, connectionsestablished by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, andother P2P group connections.

The APs 102 and STAs 104 may function and communicate (via therespective communication links 108) according to the IEEE 802.11 familyof wireless communication protocol standards (such as that defined bythe IEEE 802.11-2016 specification or amendments thereof including, butnot limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az,802.11ba and 802.11be). These standards define the WLAN radio andbaseband protocols for the PHY and medium access control (MAC) layers.The APs 102 and STAs 104 transmit and receive wireless communications(hereinafter also referred to as “Wi-Fi communications”) to and from oneanother in the form of physical layer convergence protocol (PLCP)protocol data units (PPDUs). The APs 102 and STAs 104 in the WLAN 100may transmit PPDUs over an unlicensed spectrum, which may be a portionof spectrum that includes frequency bands traditionally used by Wi-Fitechnology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band,the 3.6 GHz band, and the 900 MHz band. Some implementations of the APs102 and STAs 104 described herein also may communicate in otherfrequency bands, such as the 6 GHz band, which may support both licensedand unlicensed communications. The APs 102 and STAs 104 also can beconfigured to communicate over other frequency bands such as sharedlicensed frequency bands, where multiple operators may have a license tooperate in the same or overlapping frequency band or bands.

Each of the frequency bands may include multiple channels (which may beused as subchannels of a larger bandwidth channel as described below).For example, PPDUs conforming to the IEEE 802.11n, 802.11ac and 802.11axstandard amendments may be transmitted over the 2.4 and 5 GHz bands,each of which is divided into multiple 20 MHz channels. As such, thesePPDUs are transmitted over a physical channel having a minimum bandwidthof 20 MHz, but larger channels can be formed through channel bonding.For example, PPDUs may be transmitted over physical channels havingbandwidths of 40 MHz, 80 MHz, 160 or 320 MHz by bonding togethermultiple 20 MHz channels (which may be referred to as subchannels).

Each PPDU is a composite structure that includes a PHY preamble and apayload in the form of a PLCP service data unit (PSDU). The informationprovided in the preamble may be used by a receiving device to decode thesubsequent data in the PSDU. In instances in which PPDUs are transmittedover a bonded channel, the preamble fields may be duplicated andtransmitted in each of the multiple component channels. The PHY preamblemay include both a first portion (or “legacy preamble”) and a secondportion (or “non-legacy preamble”). The first portion may be used forpacket detection, automatic gain control and channel estimation, amongother uses. The first portion also may generally be used to maintaincompatibility with legacy devices as well as non-legacy devices. Theformat of, coding of, and information provided in the second portion ofthe preamble is based on the particular IEEE 802.11 protocol to be usedto transmit the payload.

FIG. 2 shows an example protocol data unit (PDU) 200 usable for wirelesscommunication between an AP and a number of STAs. For example, the PDU200 can be configured as a PPDU. As shown, the PDU 200 includes a PHYpreamble 201 and a PHY payload 204. For example, the preamble 201 mayinclude a first portion 202 that itself includes a legacy short trainingfield (L-STF) 206, which may consist of two BPSK symbols, a legacy longtraining field (L-LTF) 208, which may consist of two BPSK symbols, and alegacy signal field (L-SIG) 210, which may consist of one BPSK symbol.The first portion 202 of the preamble 201 may be configured according tothe IEEE 802.11a wireless communication protocol standard. The preamble201 may also include a second portion 203 including one or morenon-legacy signal fields 212, for example, conforming to an IEEEwireless communication protocol such as the IEEE 802.11ac, 802.11ax,802.11be or later wireless communication protocol standards.

L-STF 206 generally enables a receiving device to perform automatic gaincontrol (AGC) and coarse timing and frequency estimation. L-LTF 208generally enables a receiving device to perform fine timing andfrequency estimation and also to perform an initial estimate of thewireless channel. L-SIG 210 generally enables a receiving device todetermine a duration of the PDU and to use the determined duration toavoid transmitting on top of the PDU. For example, L-STF 206, L-LTF 208and L-SIG 210 may be modulated according to a binary phase shift keying(BPSK) modulation scheme. The payload 204 may be modulated according toa BPSK modulation scheme, a quadrature BPSK (Q-BPSK) modulation scheme,a quadrature amplitude modulation (QAM) modulation scheme, or anotherappropriate modulation scheme. The payload 204 may include a PSDUincluding a data field (DATA) 214 that, in turn, may carry higher layerdata, for example, in the form of medium access control (MAC) protocoldata units (MPDUs) or an aggregated MPDU (A-MPDU).

FIG. 2 also shows an example L-SIG 210 in the PDU 200. L-SIG 210includes a data rate field 222, a reserved bit 224, a length field 226,a parity bit 228, and a tail field 230. The data rate field 222indicates a data rate (note that the data rate indicated in the datarate field 212 may not be the actual data rate of the data carried inthe payload 204). The length field 226 indicates a length of the packetin units of, for example, symbols or bytes. The parity bit 228 may beused to detect bit errors. The tail field 230 includes tail bits thatmay be used by the receiving device to terminate operation of a decoder(for example, a Viterbi decoder). The receiving device may utilize thedata rate and the length indicated in the data rate field 222 and thelength field 226 to determine a duration of the packet in units of, forexample, microseconds (μs) or other time units.

FIG. 3A shows another example PDU 300 usable for wireless communicationbetween an AP and a number of STAs. The PDU 300 includes a PHY preambleincluding a first portion 302 and a second portion 304. The PDU 300 mayfurther include a PHY payload 306 after the preamble, for example, inthe form of a PSDU including a DATA field 322. The first portion 302 ofthe preamble includes L-STF 308, L-LTF 310, and L-SIG 312. The secondportion 304 of the preamble and the DATA field 322 may be formatted as aVery High Throughput (VHT) preamble and frame, respectively, inaccordance with the IEEE 802.11ac amendment to the IEEE 802.11 wirelesscommunication protocol standard. The second portion 304 includes a firstVHT signal field (VHT-SIG-A) 314, a VHT short training field (VHT-STF)316, a number of VHT long training fields (VHT-LTFs) 318, and a secondVHT signal field (VHT-SIG-B) 320 encoded separately from VHT-SIG-A 314.Like L-STF 308, L-LTF 310, and L-SIG 312, the information in VHT-SIG-A314 may be duplicated and transmitted in each of the component 20 MHzsubchannels in instances involving the use of a bonded channel.

VHT-STF 316 may be used to improve automatic gain control estimation ina MIMO transmission. VHT-LTFs 318 may be used for MIMO channelestimation and pilot subcarrier tracking. The preamble may include oneVHT-LTF 318 for each spatial stream the preamble is transmitted on.VHT-SIG-A 314 may indicate to VHT-compatible APs 102 and STAs 104 thatthe PPDU is a VHT PPDU. VHT-SIG-A 314 includes signaling information andother information usable by STAs 104 to decode VHT-SIG-B 320. VHT-SIG-A314 may indicate a bandwidth (BW) of the packet, the presence ofspace-time block coding (STBC), the number NsTs of space-time streamsper user, a Group ID indicating the group and user position assigned toa STA, a partial association identifier that may combine the AID and theBSSID, a short guard interval (GI) indication, a single-user/multi-user(SU/MU) coding indicating whether convolutional or LDPC coding is used,a modulation and coding scheme (MCS), an indication of whether abeamforming matrix has been applied to the transmission, a cyclicredundancy check (CRC) and a tail. VHT-SIG-B 320 may be used for MUtransmissions and may contain the actual data rate and MPDU or A-MPDUlength values for each of the multiple STAs 104, as well as signalinginformation usable by the STAs 104 to decode data received in the DATAfield 322, including, for example, an MCS and beamforming information.

FIG. 3B shows another example PDU 350 usable for wireless communicationbetween an AP and a number of STAs. The PDU 350 may be used for MU-OFDMAor MU-MIMO transmissions. The PDU 350 includes a PHY preamble includinga first portion 352 and a second portion 354. The PDU 350 may furtherinclude a PHY payload 356 after the preamble, for example, in the formof a PSDU including a DATA field 374. The first portion 352 includesL-STF 358, L-LTF 360, and L-SIG 362. The second portion 354 of thepreamble and the DATA field 374 may be formatted as a High Efficiency(HE) WLAN preamble and frame, respectively, in accordance with the IEEE802.11ax amendment to the IEEE 802.11 wireless communication protocolstandard. The second portion 354 includes a repeated legacy signal field(RL-SIG) 364, a first HE signal field (HE-SIG-A) 366, a second HE signalfield (HE-SIG-B) 368 encoded separately from HE-SIG-A 366, an HE shorttraining field (HE-STF) 370 and a number of HE long training fields(HE-LTFs) 372. Like L-STF 358, L-LTF 360, and L-SIG 362, the informationin RL-SIG 364 and HE-SIG-A 366 may be duplicated and transmitted in eachof the component 20 MHz subchannels in instances involving the use of abonded channel. In contrast, HE-SIG-B 368 may be unique to each 20 MHzsubchannel and may target specific STAs 104.

RL-SIG 364 may indicate to HE-compatible STAs 104 that the PPDU is an HEPPDU. An AP 102 may use HE-SIG-A 366 to identify and inform multipleSTAs 104 that the AP has scheduled UL or DL resources for them. HE-SIG-A366 may be decoded by each HE-compatible STA 104 served by the AP 102.HE-SIG-A 366 includes information usable by each identified STA 104 todecode an associated HE-SIG-B 368. For example, HE-SIG-A 366 mayindicate the frame format, including locations and lengths of HE-SIG-Bs368, available channel bandwidths, and modulation and coding schemes(MCSs), among other possibilities. HE-SIG-A 366 also may include HE WLANsignaling information usable by STAs 104 other than the number ofidentified STAs 104.

HE-SIG-B 368 may carry STA-specific scheduling information such as, forexample, per-user MCS values and per-user RU allocation information. Inthe context of DL MU-OFDMA, such information enables the respective STAs104 to identify and decode corresponding RUs in the associated datafield. Each HE-SIG-B 368 includes a common field and at least oneSTA-specific (“user-specific”) field. The common field can indicate RUdistributions to multiple STAs 104, indicate the RU assignments in thefrequency domain, indicate which RUs are allocated for MU-MIMOtransmissions and which RUs correspond to MU-OFDMA transmissions, andthe number of users in allocations, among other possibilities. Thecommon field may be encoded with common bits, CRC bits, and tail bits.The user-specific fields are assigned to particular STAs 104 and may beused to schedule specific RUs and to indicate the scheduling to otherWLAN devices. Each user-specific field may include multiple user blockfields (which may be followed by padding). Each user block field mayinclude two user fields that contain information for two respective STAsto decode their respective RU payloads in DATA field 374.

FIG. 4 shows an example PPDU 400 usable for communications between an AP102 and a number of STAs 104. As described above, each PPDU 400 includesa PHY preamble 402 and a PSDU 404. Each PSDU 404 may carry one or moreMAC protocol data units (MPDUs). For example, each PSDU 404 may carry anaggregated MPDU (A-MPDU) 408 that includes an aggregation of multipleA-MPDU subframes 406. Each A-MPDU subframe 406 may include a MACdelimiter 410 and a MAC header 412 prior to the accompanying MPDU 414,which comprises the data portion (“payload” or “frame body”) of theA-MPDU subframe 406. The MPDU 414 may carry one or more MAC service dataunit (MSDU) subframes 416. For example, the MPDU 414 may carry anaggregated MSDU (A-MSDU) 418 including multiple MSDU subframes 416. EachMSDU subframe 416 contains a corresponding MSDU 420 preceded by asubframe header 422.

Referring back to the A-MPDU subframe 406, the MAC header 412 mayinclude a number of fields containing information that defines orindicates characteristics or attributes of data encapsulated within theframe body 414. The MAC header 412 also includes a number of fieldsindicating addresses for the data encapsulated within the frame body414. For example, the MAC header 412 may include a combination of asource address, a transmitter address, a receiver address or adestination address. The MAC header 412 may include a frame controlfield containing control information. The frame control field specifiesthe frame type, for example, a data frame, a control frame, or amanagement frame. The MAC header 412 may further including a durationfield indicating a duration extending from the end of the PPDU until theend of an acknowledgment (ACK) of the last PPDU to be transmitted by thewireless communication device (for example, a block ACK (BA) in the caseof an A-MPDU). The use of the duration field serves to reserve thewireless medium for the indicated duration, thus establishing the NAV.Each A-MPDU subframe 406 may also include a frame check sequence (FCS)field 424 for error detection. For example, the FCS field 416 mayinclude a cyclic redundancy check (CRC).

As described above, APs 102 and STAs 104 can support multi-user (MU)communications; that is, concurrent transmissions from one device toeach of multiple devices (for example, multiple simultaneous downlink(DL) communications from an AP 102 to corresponding STAs 104), orconcurrent transmissions from multiple devices to a single device (forexample, multiple simultaneous uplink (UL) transmissions fromcorresponding STAs 104 to an AP 102). To support the MU transmissions,the APs 102 and STAs 104 may utilize multi-user multiple-input,multiple-output (MU-MIMO) and multi-user orthogonal frequency divisionmultiple access (MU-OFDMA) techniques.

In MU-OFDMA schemes, the available frequency spectrum of the wirelesschannel may be divided into multiple resource units (RUs) each includinga number of different frequency subcarriers (“tones”). Different RUs maybe allocated or assigned by an AP 102 to different STAs 104 atparticular times. The sizes and distributions of the RUs may be referredto as an RU allocation. In some implementations, RUs may be allocated in2 MHz intervals, and as such, the smallest RU may include 26 tonesconsisting of 24 data tones and 2 pilot tones. Consequently, in a 20 MHzchannel, up to 9 RUs (such as 2 MHz, 26-tone RUs) may be allocated(because some tones are reserved for other purposes). Similarly, in a160 MHz channel, up to 74 RUs may be allocated. Larger 52 tone, 106tone, 242 tone, 484 tone and 996 tone RUs may also be allocated.Adjacent RUs may be separated by a null subcarrier (such as a DCsubcarrier), for example, to reduce interference between adjacent RUs,to reduce receiver DC offset, and to avoid transmit center frequencyleakage.

For UL MU transmissions, an AP 102 can transmit a trigger frame toinitiate and synchronize an UL MU-OFDMA or UL MU-MIMO transmission frommultiple STAs 104 to the AP 102. Such trigger frames may thus enablemultiple STAs 104 to send UL traffic to the AP 102 concurrently in time.A trigger frame may address one or more STAs 104 through respectiveassociation identifiers (AIDs), and may assign each AID (and thus eachSTA 104) one or more RUs that can be used to send UL traffic to the AP102. The AP also may designate one or more random access (RA) RUs thatunscheduled STAs 104 may contend for.

APs and STAs that include multiple antennas may support variousdiversity schemes. For example, spatial diversity may be used by one orboth of a transmitting device or a receiving device to increase therobustness of a transmission. For example, to implement a transmitdiversity scheme, a transmitting device may transmit the same dataredundantly over two or more antennas. APs and STAs that includemultiple antennas may also support space-time block coding (STBC). WithSTBC, a transmitting device also transmits multiple copies of a datastream across a number of antennas to exploit the various receivedversions of the data to increase the likelihood of decoding the correctdata. More specifically, the data stream to be transmitted is encoded inblocks, which are distributed among the spaced antennas and across time.Generally, STBC can be used when the number N_(Tx) of transmit antennasexceeds the number N_(SS) of spatial streams (described below). TheN_(SS) spatial streams may be mapped to a number N_(STS) of space-timestreams, which are then mapped to N_(Tx) transmit chains.

APs and STAs that include multiple antennas may also support spatialmultiplexing, which may be used to increase the spectral efficiency andthe resultant throughput of a transmission. To implement spatialmultiplexing, the transmitting device divides the data stream into anumber N_(SS) of separate, independent spatial streams. The spatialstreams are then separately encoded and transmitted in parallel via themultiple N_(Tx) transmit antennas. If the transmitting device includesN_(Tx) transmit antennas and the receiving device includes N_(Rx)receive antennas, the maximum number N_(SS) of spatial streams that thetransmitting device can simultaneously transmit to the receiving deviceis limited by the lesser of N_(Tx) and N_(Rx). In some implementations,the AP 102 and STAs 104 may be able to implement both transmit diversityas well as spatial multiplexing. For example, in instances in which thenumber N_(SS) of spatial streams is less than the number N_(Tx) oftransmit antennas, the spatial streams may be multiplied by a spatialexpansion matrix to achieve transmit diversity.

APs and STAs that include multiple antennas may also supportbeamforming. Beamforming refers to the focusing of the energy of atransmission in the direction of a target receiver. Beamforming may beused both in a single-user context, for example, to improve asignal-to-noise ratio (SNR), as well as in a multi-user (MU) context,for example, to enable MU multiple-input multiple-output (MIMO)(MU-MIMO) transmissions (also referred to as spatial division multipleaccess (SDMA)). To perform beamforming, a transmitting device, referredto as the beamformer, transmits a signal from each of multiple antennas.The beamformer configures the amplitudes and phase shifts between thesignals transmitted from the different antennas such that the signalsadd constructively along particular directions towards the intendedreceiver, which is referred to as a beamformee. The manner in which thebeamformer configures the amplitudes and phase shifts depends on channelstate information (CSI) associated with the wireless channels over whichthe beamformer intends to communicate with the beamformee.

To obtain the CSI necessary for beamforming, the beamformer may performa channel sounding procedure with the beamformee. For example, thebeamformer may transmit one or more sounding signals (for example, inthe form of a null data packet (NDP)) to the beamformee. The beamformeemay then perform measurements for each of the N_(Tx)×N_(Rx) sub-channelscorresponding to all of the transmit antenna and receive antenna pairsbased on the sounding signal. The beamformee generates a feedback matrixbased on the channel measurements and, typically, compresses thefeedback matrix before transmitting the feedback to the beamformer. Thebeamformer may then generate a precoding (or “steering”) matrix for thebeamformee based on the feedback and use the steering matrix to precodethe data streams to configure the amplitudes and phase shifts forsubsequent transmissions to the beamformee.

As described above, a transmitting device may support the use ofdiversity schemes. When performing beamforming, the transmittingbeamforming array gain is logarithmically proportional to the ratio ofN_(Tx) to N_(SS). As such, it is generally desirable, within otherconstraints, to increase the number N_(Tx) of transmit antennas whenperforming beamforming to increase the gain. It is also possible to moreaccurately direct transmissions by increasing the number of transmitantennas. This is especially advantageous in MU transmission contexts inwhich it is particularly important to reduce inter-user interference.

FIG. 5 shows a block diagram of an example wireless communication device500. In some implementations, the wireless communication device 500 canbe an example of a device for use in a STA such as one of the STAs 104described above with reference to FIG. 1. In some implementations, thewireless communication device 500 can be an example of a device for usein an AP such as the AP 102 described above with reference to FIG. 1.The wireless communication device 500 is capable of transmitting (oroutputting for transmission) and receiving wireless communications (forexample, in the form of wireless packets). For example, the wirelesscommunication device can be configured to transmit and receive packetsin the form of PPDUs and MPDUs conforming to an IEEE 802.11 standard,such as that defined by the IEEE 802.11-2016 specification or amendmentsthereof including, but not limited to, 802.11ah, 802.11ad, 802.11ay,802.11ax, 802.11az, 802.11ba and 802.11be.

The wireless communication device 500 can be, or can include, a chip,system on chip (SoC), chipset, package or device that includes one ormore modems 502, for example, a Wi-Fi (IEEE 802.11 compliant) modem. Insome implementations, the one or more modems 502 (collectively “themodem 502”) additionally include a WWAN modem (for example, a 3GPP 4GLTE or 5G compliant modem). In some implementations, the wirelesscommunication device 500 also includes one or more radios 504(collectively “the radio 504”). In some implementations, the wirelesscommunication device 506 further includes one or more processors,processing blocks or processing elements 506 (collectively “theprocessor 506”) and one or more memory blocks or elements 508(collectively “the memory 508”).

The modem 502 can include an intelligent hardware block or device suchas, for example, an application-specific integrated circuit (ASIC) amongother possibilities. The modem 502 is generally configured to implementa PHY layer. For example, the modem 502 is configured to modulatepackets and to output the modulated packets to the radio 504 fortransmission over the wireless medium. The modem 502 is similarlyconfigured to obtain modulated packets received by the radio 504 and todemodulate the packets to provide demodulated packets. In addition to amodulator and a demodulator, the modem 502 may further include digitalsignal processing (DSP) circuitry, automatic gain control (AGC), acoder, a decoder, a multiplexer and a demultiplexer. For example, whilein a transmission mode, data obtained from the processor 506 is providedto a coder, which encodes the data to provide encoded bits. The encodedbits are then mapped to points in a modulation constellation (using aselected MCS) to provide modulated symbols. The modulated symbols maythen be mapped to a number N_(SS) of spatial streams or a number N_(STS)of space-time streams. The modulated symbols in the respective spatialor space-time streams may then be multiplexed, transformed via aninverse fast Fourier transform (IFFT) block, and subsequently providedto the DSP circuitry for Tx windowing and filtering. The digital signalsmay then be provided to a digital-to-analog converter (DAC). Theresultant analog signals may then be provided to a frequencyupconverter, and ultimately, the radio 504. In implementations involvingbeamforming, the modulated symbols in the respective spatial streams areprecoded via a steering matrix prior to their provision to the IFFTblock.

While in a reception mode, digital signals received from the radio 504are provided to the DSP circuitry, which is configured to acquire areceived signal, for example, by detecting the presence of the signaland estimating the initial timing and frequency offsets. The DSPcircuitry is further configured to digitally condition the digitalsignals, for example, using channel (narrowband) filtering, analogimpairment conditioning (such as correcting for I/Q imbalance), andapplying digital gain to ultimately obtain a narrowband signal. Theoutput of the DSP circuitry may then be fed to the AGC, which isconfigured to use information extracted from the digital signals, forexample, in one or more received training fields, to determine anappropriate gain. The output of the DSP circuitry also is coupled withthe demodulator, which is configured to extract modulated symbols fromthe signal and, for example, compute the logarithm likelihood ratios(LLRs) for each bit position of each subcarrier in each spatial stream.The demodulator is coupled with the decoder, which may be configured toprocess the LLRs to provide decoded bits. The decoded bits from all ofthe spatial streams are then fed to the demultiplexer fordemultiplexing. The demultiplexed bits may then be descrambled andprovided to the MAC layer (the processor 506) for processing, evaluationor interpretation.

The radio 504 generally includes at least one radio frequency (RF)transmitter (or “transmitter chain”) and at least one RF receiver (or“receiver chain”), which may be combined into one or more transceivers.For example, the RF transmitters and receivers may include various DSPcircuitry including at least one power amplifier (PA) and at least onelow-noise amplifier (LNA), respectively. The RF transmitters andreceivers may in turn be coupled to one or more antennas. For example,in some implementations, the wireless communication device 500 caninclude, or be coupled with, multiple transmit antennas (each with acorresponding transmit chain) and multiple receive antennas (each with acorresponding receive chain). The symbols output from the modem 502 areprovided to the radio 504, which then transmits the symbols via thecoupled antennas. Similarly, symbols received via the antennas areobtained by the radio 504, which then provides the symbols to the modem502.

The processor 506 can include an intelligent hardware block or devicesuch as, for example, a processing core, a processing block, a centralprocessing unit (CPU), a microprocessor, a microcontroller, a digitalsignal processor (DSP), an application-specific integrated circuit(ASIC), a programmable logic device (PLD) such as a field programmablegate array (FPGA), discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. The processor 506 processes information receivedthrough the radio 504 and the modem 502, and processes information to beoutput through the modem 502 and the radio 504 for transmission throughthe wireless medium. For example, the processor 506 may implement acontrol plane and MAC layer configured to perform various operationsrelated to the generation and transmission of MPDUs, frames or packets.The MAC layer is configured to perform or facilitate the coding anddecoding of frames, spatial multiplexing, space-time block coding(STBC), beamforming, and OFDMA resource allocation, among otheroperations or techniques. In some implementations, the processor 506 maygenerally control the modem 502 to cause the modem to perform variousoperations described above.

The memory 504 can include tangible storage media such as random-accessmemory (RAM) or read-only memory (ROM), or combinations thereof. Thememory 504 also can store non-transitory processor- orcomputer-executable software (SW) code containing instructions that,when executed by the processor 506, cause the processor to performvarious operations described herein for wireless communication,including the generation, transmission, reception and interpretation ofMPDUs, frames or packets. For example, various functions of componentsdisclosed herein, or various blocks or steps of a method, operation,process or algorithm disclosed herein, can be implemented as one or moremodules of one or more computer programs.

FIG. 6A shows a block diagram of an example AP 602. For example, the AP602 can be an example implementation of the AP 102 described withreference to FIG. 1. The AP 602 includes a wireless communication device(WCD) 610. For example, the wireless communication device 610 may be anexample implementation of the wireless communication device 500described with reference to FIG. 5. The AP 602 also includes multipleantennas 620 coupled with the wireless communication device 610 totransmit and receive wireless communications. In some implementations,the AP 602 additionally includes an application processor 630 coupledwith the wireless communication device 610, and a memory 640 coupledwith the application processor 630. The AP 602 further includes at leastone external network interface 650 that enables the AP 602 tocommunicate with a core network or backhaul network to gain access toexternal networks including the Internet. For example, the externalnetwork interface 650 may include one or both of a wired (for example,Ethernet) network interface and a wireless network interface (such as aWWAN interface). Ones of the aforementioned components can communicatewith other ones of the components directly or indirectly, over at leastone bus. The AP 602 further includes a housing that encompasses thewireless communication device 610, the application processor 630, thememory 640, and at least portions of the antennas 620 and externalnetwork interface 650.

FIG. 6B shows a block diagram of an example STA 604. For example, theSTA 604 can be an example implementation of the STA 104 described withreference to FIG. 1. The STA 604 includes a wireless communicationdevice 615. For example, the wireless communication device 615 may be anexample implementation of the wireless communication device 500described with reference to FIG. 5. The STA 604 also includes one ormore antennas 625 coupled with the wireless communication device 615 totransmit and receive wireless communications. The STA 604 additionallyincludes an application processor 635 coupled with the wirelesscommunication device 615, and a memory 645 coupled with the applicationprocessor 635. In some implementations, the STA 604 further includes auser interface (UI) 655 (such as a touchscreen or keypad) and a display665, which may be integrated with the UI 655 to form a touchscreendisplay. In some implementations, the STA 604 may further include one ormore sensors 675 such as, for example, one or more inertial sensors,accelerometers, temperature sensors, pressure sensors, or altitudesensors. Ones of the aforementioned components can communicate withother ones of the components directly or indirectly, over at least onebus. The STA 604 further includes a housing that encompasses thewireless communication device 615, the application processor 635, thememory 645, and at least portions of the antennas 625, UI 655, anddisplay 665.

Aspects of the present disclosure recognize that wireless communicationsconforming to the IEEE 802.11 family of standards may be well-suited forRF sensing. RF sensing is a technique for sensing objects or movement inan environment based, at least in part, on the transmission andreception of electromagnetic signals. More specifically, changes in theenvironment can be detected based on changes in the wirelesscommunication channel between the transmitting device and the receivingdevice. For example, the presence or movement of objects in theenvironment may interfere with or otherwise alter the phase or amplitudeof wireless communication signals transmitted from a transmitting deviceto a receiving device, and thus, the wireless channel. The range ofapplications or accuracy of RF sensing may depend on the amount ordetail of information communicated between the transmitting device andthe receiving device.

As described above, existing IEEE 802.11 standards define a channelsounding procedure, for beamforming, whereby a beamformer transmitssounding signals (in the form of NDPs) to a beamformee. The beamformeemay perform measurements on the wireless channel based on the receivedsounding signals. The beamformee then generates a compressed feedbackmatrix based on the channel measurements and transmits the compressedfeedback matrix back to the beamformer. However, due to compression, thefeedback matrix may not be suitable for some RF sensing applications.For example, small changes in the environment (such as a personbreathing) may not translate to detectable changes in a compressedfeedback matrix associated therewith. Changes in the feedback matrix canalso be attributed to changes in the transmission parameters of thetransmitting device or changes in the reception parameters of thereceiving device. However, neither the sounding signals nor the feedbackmatrices defined by existing IEEE 802.11 standards provide adequateindication of the transmission parameters or the reception parameters.

In some implementations, a wireless communication network conforming tothe IEEE 802.11 family of standards (such as a WLAN) may be used toimplement an RF sensing system. A transmitting device may transmit asounding dataset, over a wireless channel, to a receiving device. Thesounding dataset may include information carried in one or more trainingfields configured for channel estimation and sounding controlinformation based, at least in part, on a configuration of thetransmitting device. The receiving device may acquire CSI for thewireless channel based on the received sounding dataset and selectivelygenerate a channel report for the wireless channel based, at least inpart, on the CSI and the sounding control information. For example, thereceiving device may generate the channel report only when thecharacteristics of the wireless channel have changed by at least athreshold amount. The channel report may indicate changes to thewireless channel which, in turn, may be used to sense objects in thevicinity of the transmitting device or the receiving device.

Particular implementations of the subject matter described in thisdisclosure can be implemented to realize one or more of the followingpotential advantages. In some implementations, the described techniquescan be used to facilitate RF sensing that can support a wide range ofapplications. For example, by including the configuration of thetransmitting device in the sounding data transmitted to the receivingdevice, the receiving device can obtain more accurate measurements ofthe wireless channel. Further, by generating channel reports only whenthe wireless channel changes by a threshold amount, aspects of thepresent disclosure may reduce the overhead associated with the channelsounding procedure.

FIGS. 7A and 7B shows an example RF sensing system 700 according to someimplementations. The RF sensing system 700 includes a transmitting (TX)device 710 and a receiving (RX) device 720. In some implementations, thetransmitting device 710 may be one example of the AP 102 of FIG. 1 orthe AP 602 of FIG. 6A. In some other implementations, the transmittingdevice 710 may be one example of the STA 104 of FIG. 1 or the STA 604 ofFIG. 6B. In some implementations, the receiving device 720 may be oneexample of the AP 102 of FIG. 1 or the AP 602 of FIG. 6A. In some otherimplementations, the receiving device 720 may be one example of the STA104 of FIG. 1 or the STA 604 of FIG. 6B.

With reference to FIG. 7A, the transmitting device 710 is configured totransmit sounding signals, over a wireless channel 730, to the receivingdevice 720. Some sounding signals may reflect off objects and surfacesin the environment before reaching the receiving device 734. As shown inFIG. 7A, a static object or surface 701 (such as a wall) is locatedalong the path of sounding signals 732. More specifically, the surface701 reflects the sounding signals 732 in a direction of the receivingdevice 720. The receiving device is configured to measure one or morecharacteristics of the wireless channel 730 based on the receivedsounding signals 732. For example, the sounding signals 732 may includeone or more training fields (such as one or more of the LTFs describedwith respect to FIGS. 2, 3A, and 3B) that can be used for channelestimation. In some implementations, the receiving device 720 maytransmit a channel report 736, based on the measured characteristics ofthe wireless channel 730, back to the transmitting device 710.

With reference to FIG. 7B, a new object 702 (such as a person) may enterthe environment of the RF sensing system 700. The transmitting device710 may transmit sounding signals 742, in the presence of the object702, to the receiving device 720. The receiving device 720 may thenmeasure one or more characteristics of a wireless channel 740 based onthe received sounding signals 742. In comparison to FIG. 7A, the newobject 702 may alter the propagation paths of at least some of thesounding signals transmitted by the transmitting device 710. Forexample, the phases or amplitudes of sounding signals received (by thereceiving device 720) in the presence of the object 702 may be differentthan the phases or amplitudes of sounding signals received in theabsence of the object 702. As a result, the wireless channel 740 may bedifferent than the wireless channel 730 previously measured by thereceiving device 720. In some implementations, the receiving device 720may transmit a channel report 746, based on the measured characteristicsof the wireless channel 740, back to the transmitting device 710.

The transmitting device 710 may detect a presence or movement of theobject 702 based on differences or changes between the wireless channel740 and the wireless channel 730. For example, the transmitting device710 may compare the characteristics of the wireless channel 740 (basedon the channel report 746) with the characteristics of the wirelesschannel 730 (based on the channel report 736) to detect changes in thewireless channel. Assuming the transmitting device 710 and the receivingdevice 720 remain static (from FIG. 7A to FIG. 7B), the differencesbetween wireless channel 730 and wireless channel 740 may be attributedto the presence or movement of the new object 702. Examplecharacteristics that may be detectable based on the changes in thewireless channel include, but are not limited to, movement (or lackthereof) of an object, movement patterns (such as walking, falling, orgestures), object tracking (such as movement direction, range, orlocation), and vital signs (such as breathing).

As described above, the range of applications for RF sensing may dependon the detail and accuracy of information communicated between thetransmitting device 710 and the receiving device 720. For example,compression may reduce the level of detail needed to detect slightchanges in the environment. In some implementations, the channel reports736 and 746 generated by the receiving device 720 may include raw oruncompressed channel state information (CSI). In some aspects, the CSImay include an in-phase (I) and quadrature (Q) representation of theassociated wireless channel. In some other aspects, the CSI may includea phase and amplitude representation of the associated wireless channel.In some implementations, the channel report may include a raw oruncompressed amplitude-only representation of the wireless channel. Insome other implementations, the channel report may include a raw oruncompressed phase-only representation of the wireless channel. Aspectsof the present disclosure recognize that an amplitude-only or phase-onlyrepresentation of the wireless channel may be sufficient for some RFsensing applications and may help reduce overhead.

In some cases, the receiving device 720 may perform pre-processing onthe channel measurement. For example, the CSI may be normalized to aparticular reference antenna of the receiving device 720. Alternatively,or in addition, the CSI may be normalized with respect to phase (and notamplitude), amplitude (and not phase), or a combination of thereof. Insome implementations, the receiving device 720 may include an indicationof the pre-processing performed on the CSI (such as an indication of thereference antenna for which the CSI is normalized) in the channel reportsent back to the transmitting device 710. In some other implementations,the receiving device may determine a level of quantization to beperformed on the CSI. The receiving device 720 may include an indicationof the quantization level of the CSI in the channel report sent back tothe transmitting device 710.

Aspects of the present disclosure recognize that the properties of thewireless channel depend on the transmission parameters of thetransmitting device 710 and the reception parameters of the receivingdevice 720, in addition to the characteristics of the environment. Inother words, changing the transmission parameters of the transmittingdevice 710 or the reception parameters of the receiving device 720,between sounding operations, may cause the receiving device 720 tomeasure different CSI responsive to each sounding even if theenvironment did not change. To accurately attribute changes in thewireless channel to changes in the environment, additional informationmay be conveyed by the transmitting device 710 to the receiving device720 (or by the receiving device 720 to the transmitting device 710) inassociation with the sounding signals.

In some implementations, the transmitting device 710 may be configuredto transmit sounding control information to the receiving device 720 inassociation with each sounding signal. The sounding control informationmay indicate a configuration of the transmitting device 710 whentransmitting a corresponding sounding signal (or set of soundingsignals) to the receiving device 720. In some aspects, the soundingcontrol information may indicate one or more transmission parametersused by the transmitting device 710 to transmit the sounding signal.Example transmission parameters may include, but are not limited to,transmit antenna indexes, transmit power per antenna, cyclic shiftdelays (CSDs), and any spatial mapping of the sounding signal todifferent transmit antennas. Thus, the indication of the transmissionparameters may be used to control for variations in CSI that couldotherwise be attributed to changes in the transmission parameters of thetransmitting device 710.

In some other aspects, the sounding control information may include asequence number for the corresponding sounding signal. The sequencenumber may provide a general indication of the transmission parametersused in transmitting the sounding signal. For example, the transmittingdevice 710 may change the sequence number for subsequent soundingsignals if the transmitting device 710 uses different transmissionparameters to transmit the subsequent sounding signals. Thus, thesequence number also may be used to control for variations in CSI thatcould otherwise be attributed to changes in the transmission parametersof the transmitting device 710.

Still further, in some aspects, the sounding control information mayinclude a timing synchronization function (TSF) value of thetransmitting device 710. The TSF value of the transmitting device 710may indicate (or may be used to determine) a time at which theassociated sounding signal is transmitted by the transmitting device710. More specifically, the TSF value may be used to determine apropagation delay between the transmission of the sounding signal by thetransmitting device 710 to the reception of the sounding signal by thereceiving device 720. The propagation delay may be useful for some RFsensing applications (such as ranging and object tracking).

In some implementations, the receiving device 720 may include at least asubset of the sounding control information in the channel reports sentback to the transmitting device 710. In some other implementations, thechannel report may indicate a configuration of the receiving device 720when receiving a corresponding sounding signal used to generate the CSIincluded in the channel report. For example, the channel report mayinclude the TSF value indicating the time at which the correspondingsounding signal was transmitted by the transmitting device 710. In someaspects, the channel report also may include a TSF value of thereceiving device 720. The TSF value of the receiving device 720 mayindicate a time at which the corresponding sounding signal was receivedby the receiving device 720. The transmitting device 710 may compare theTSF value of the receiving device 720 with the TSF value of thetransmitting device 710 to determine the propagation delay of thecorresponding sounding signal.

Additionally, or alternatively, the channel report may include thesequence number of the corresponding sounding signal. In some aspects,the channel report may indicate a change in the sequence number (such aswith a new sequence number) if the reception parameters used to receivethe corresponding sounding signal are different the reception parameterspreviously used to receive other sounding signals having the samesequence number. To control for variations in CSI that could otherwisebe attributed to changes in transmission parameters or receptionparameters, the transmitting device 710 may compare only the CSIreported by the receiving device 720 against other CSI associated withthe same sequence number.

Still further, in some implementations, the channel report may indicateone or more reception parameters used by the receiving device 720 toreceive the corresponding sounding signal. Example reception parametersmay include, but are not limited to, receive antenna indexes, automaticgain control (AGC) per receive chain, estimated carrier frequency offset(CFO) or pre-correction, receive signal strength indication (RSSI) perantenna, or any spatial mapping of the sounding signal to differentreceive antennas. To control for variation in CSI that could otherwisebe attributed to changes in reception parameters, the transmittingdevice 710 may compare only the CSI reported by the receiving device 720against other CSI associated with at least the same receptionparameters.

The sounding control information and the training fields (used forchannel estimation) may be collectively referred to as a soundingdataset. In some implementations, the sounding dataset may betransmitted as a single sounding packet or PDU. For example, thesounding control information and the training fields may be included indifferent portions of the same sounding packet. Alternatively, oradditionally, at least some of the sounding control information may beincluded in the same portion of the sounding packet that includes thetraining fields. In some other implementations, the sounding dataset maybe distributed across multiple packets. For example, the training fieldsmay be included in a sounding packet or PDU and the sounding controlinformation may be included in a separate message or packet associatedwith (or immediately preceding) the sounding packet or PDU.

FIG. 8A shows an example sounding dataset 800A usable for RF sensingaccording to some implementations. In some implementations, the soundingdataset 800A may be one example of any of the sounding signals 732 or742 of FIGS. 7A and 7B, respectively. The sounding dataset 800A includessounding control information 812 and one or more training fields 822that may be used for channel estimation. As shown in FIG. 8A, thesounding control information 812 is included in a null data packetannouncement (NDPA) 810 and the training fields 822 are included in anull data packet (NDP) 820 immediately following the NDPA 810. The NDP820 and the NDPA 810 may be separated by a short interframe space (SIFS)duration.

In some implementations, the sounding control information 812 mayindicate a configuration of the transmitting device to be used intransmitting the sounding dataset 800A (such as described with respectto FIGS. 7A and 7B). In some other implementations, the sounding controlinformation 812 may indicate one or more parameters to be used by areceiving device to encode a channel report. Example encoding parametersmay include, but are not limited to, a minimum or maximum quantizationlevel for the CSI, a bandwidth or resource unit (RU) allocation, anumber of spatial streams, or one or more antenna indexes. Stillfurther, in some implementations, the sounding control information 812may identify a group of receiving devices as intended recipients of thesounding dataset 800A.

FIG. 8B shows another example sounding dataset 800B usable for RFsensing according to some implementations. In some implementations, thesounding dataset 800B may be one example of any of the sounding signals732 or 742 of FIGS. 7A and 7B, respectively. As shown in FIG. 8B, thesounding control information 812 and the training fields 822 areincluded in a single PPDU 850. More specifically, the training fields822 are included in a PHY preamble 830 of the PPDU 850 while thesounding control information 812 is included in a payload 840 of thePPDU 850. In some implementations, the PPDU 850 may be a sounding PPDUsuch as defined by existing or future IEEE 802.11 standards. In thiscase, the training fields 822 may include sounding LTFs that areconfigured for full channel estimation. In some other implementations,the PPDU 850 may be a data PPDU such as defined by existing or futureIEEE 802.11 standards. In this case, the training fields 822 may includestandard LTFs that can be used for channel estimation limited to theMIMO configuration used for transmitting the PPDU 850. Still further, insome implementations, the payload 840 also may include data 842 intendedfor the receiving device(s).

FIG. 8C shows another example sounding dataset 800C usable for RFsensing according to some implementations. In some implementations, thesounding dataset 800C may be one example of any of the sounding signals732 or 742 of FIGS. 7A and 7B, respectively. As shown in FIG. 8C, thesounding control information 812 and the training fields 822 areincluded in a single PPDU 880. More specifically, the sounding controlinformation 812 and the training fields 822 are included together in aPHY preamble 860 of the PPDU 880. The PPDU 880 may correspond to a newPPDU format that is not defined by existing IEEE 802.11 standards. Insome implementations, the PPDU 880 may further include a payload 870which may include data 872 intended for the receiving device(s).

As described above, the receiving device in an RF sensing system maygenerate a channel report based on a received sounding dataset. Thechannel report may include raw or uncompressed CSI as well as additionalinformation that may be used to characterize the wireless channel. Toreduce overhead, the channel reports may be generated or transmittedless frequently than the sounding datasets. In some implementations, thereceiving device may generate a channel report only after receiving anumber (n) of sounding datasets from the transmitting device. In someother implementations, the receiving device may generate a channelreport only after one or more conditions are satisfied. Still further,in some implementations, the receiving device may not transmit anychannel reports to the transmitting device. For example, some receivingdevices (rather than transmitting devices) may be configured tointerpret differences in CSI for RF sensing purposes. Alternatively, oradditionally, the transmitting device and the receiving device may becommunicatively coupled to a shared backhaul. To further reduce wirelesscommunications overhead, the receiving device may provide the channelreports to the backhaul rather than transmit the channel reports overthe wireless medium.

FIG. 9 shows a timing diagram illustrating an example message exchangebetween a transmitting (TX) device and a receiving (RX) device in an RFsensing system according to some implementations. In someimplementations, the TX device and the RX device may be examples of thetransmitting device 710 and the receiving device 720, respectively, ofFIGS. 7A and 7B. For simplicity, only one RX device is shown in FIG. 9.However, in actual implementations, the RF sensing system may includeany number of RX devices.

In some implementations, the TX device may transmit a control ormanagement frame 910 to the RX device at time to. The control ormanagement frame 910 may include sounding control information that isgenerally applicable to a number (n) of datasets 920(1)-920(n) to betransmitted as part of an RF sensing procedure. As described above, eachof the sounding dataset 920(1)-920(n) may include sounding controlinformation which may indicate a configuration of the TX device at thetime the respective sounding datasets is transmitted, one or moreparameters to be used by a receiving device to encode a channel report,or a group of RX devices to receive the sounding datasets. To reduceoverhead, any sounding control information that is common to thesounding datasets 920(1)-920(n) may be included in the controlmanagement frame 910 (rather than in individual sounding datasets).

In some implementations, the sounding control information included inthe control or management frame 910 (or alternatively, in one or more ofthe sounding datasets 920(1)-920(n)) may indicate one or more conditionsfor generating or transmitting a channel report. In some aspects, the TXdevice may require the RX device to generate channel reports based onaggregated data from multiple sounding datasets. For example, thesounding control information may indicate that the RX device shouldreceive all n sounding datasets 920(1)-9201(n) before generating achannel report (if at all). In some other aspects, the TX device mayrequire the RX device to generate a channel report only if the RSSI of acorresponding dataset exceeds an RSSI threshold. For example, CSIgenerated from a weak sounding signal may be less accurate or reliablethan CSI generated from stronger sounding signals. Thus, the soundingcontrol information may indicate the RSSI threshold that must besatisfied in order to generate a corresponding channel report.

Aspects of the present disclosure recognize that RF sensing techniquesdepend on changing channel conditions to detect objects or movement inthe environment. Thus, to reduce overhead, the RX device may report onlydifferences in CSI from two or more sounding datasets. The soundingcontrol information included in the control or management frame 910 (orin one or more of the sounding datasets) may indicate which of thesounding datasets 920(1)-920(n) is to be used as a “reference” datasetin determining the difference in CSI. Alternatively, or additionally,the sounding control information included in the control or managementframe 910 may identify multiple reference datasets among the soundingdatasets 920(1)-920(n) and the RX device may be separately notified asto which of the reference datasets to use in generating a particularchannel report. In some implementations, the RX device may require theTX device to generate a channel report only if the difference in CSIexceeds a threshold amount. For example, the sounding controlinformation may indicate the CSI threshold that must be satisfied togenerate a channel report.

At time t₁, the TX device transmits a first sounding dataset 920(1) tothe RX device. In some implementations, the sounding dataset 920(1) maybe one example of any of the sounding datasets 800A-800C described withrespect to FIGS. 8A-8C, respectively. The sounding dataset 920(1) mayinclude sounding control information and one or more training fields tobe used by the RX device to obtain a first measurement of the wirelesscommunications channel between the TX device and the RX device. In someimplementations, the sounding control information may indicate whetherthe first sounding dataset 920(1) corresponds to a reference dataset.Assuming the first sounding dataset 920(1) is a reference dataset, theRX device may store the CSI acquired from the sounding dataset 920(1) asa reference CSI.

At time t2, the TX device transmits an n^(th) sounding dataset 920(n) tothe RX device. In some implementations, the sounding dataset 920(n) alsomay be one example of any of the sounding datasets 800A-800C describedwith respect to FIGS. 8A-8C, respectively. The sounding dataset 920(n)may include sounding control information and one or more training fieldsto be used by the RX device to obtain an n^(th) measurement of thewireless communications channel between the TX device and the RX device.Since the sounding dataset 920(n) is the final dataset in the soundingsequence, the RX device may selectively transmit a channel report 930back to the TX device at time t3. As described above, the channel report930 may include a subset of the sounding control information receivedfrom the TX device. Additionally, or alternatively, the channel report930 may indicate a configuration of the RX device at the time one ormore of the sounding datasets 920(1)-920(n) was received.

In some implementations, the channel report 930 may include an averageor aggregate CSI measured by the RX device based the received soundingdatasets 920(1)-920(n). In some other implementations, the channelreport 930 may include a difference in the CSI acquired based on then^(th) sounding dataset 920(n) and a reference CSI (such as the CSIacquired based on the first sounding dataset 920(1)). For example, thedifference in CSI may be expressed as an error vector magnitude (EVM).In some implementations, the RX device may determine a level ofquantization to be performed on the difference in CSI. For example, theRX device may select any quantization level that conforms to the maximumor minimum quantization thresholds indicated in the sounding controlinformation. The RX device may include an indication of the quantizationlevel in the channel report 930.

In some implementations, the RX device may generate or transmit achannel report only if one or more conditions are satisfied. Forexample, the reporting conditions may be indicated in the soundingcontrol information received from the TX device. In some aspects, the RXdevice may not generate a channel report if the RSSI thresholdassociated with the received sounding datasets 920(1)-920(n) is below anRSSI threshold. In some other aspects, the RX device may not generate achannel report if the difference in the CSI is below a CSI threshold.Still further, in some aspects, the RX device also may not generate achannel report if it was unable to correctly receive or decode one ormore of the sounding datasets 920(1)-920(n). For example, the RX devicemay fail to receive one or more of the sounding datasets 920(1)-920(n)as a result of too much interference on the wireless channel, a failedcyclic redundancy check (CRC), among other examples.

In some implementations, the RX device may transmit a response to the TXdevice, at time t3, even if no channel report was generated. Forexample, the response may provide a reason for which no channel reportwas generated or indicate which reporting conditions were not satisfied.Alternatively, the response may be a short acknowledgement frame (ACK orQoS null) which does not include a channel report. In some otherimplementations, the RX device may not send any response to the TXdevice at time t3. As described above, the TX device may not expect toreceive any channel report or response from the RX device in some RFsensing configurations (such as where the RX device performs RF sensingor the TX device and the RX device are communicatively coupled to ashared backhaul). The TX device also may explicitly indicate, in thesounding control information, that no channel report is to be sent backto the TX device.

In the example of FIG. 9, the RX device selectively generates a channelreport for every n sounding datasets (where n is depicted as an integernumber greater than 1). However, in some other implementations, the RXdevice may selectively generate channel reports after each soundingdataset received from the TX device. As described above, the channelreport may include raw or uncompressed CSI or a difference in CSIacquired in response to each sounding dataset received from the TXdevice. In some implementations, the RX device may use the CSI acquiredfrom the most recent sounding dataset as a reference CSI to be comparedagainst the CSI acquired from the next sounding dataset received fromthe TX device. In some other implementations, the RX device may comparethe reference CSI against the CSI acquired from the n^(th) soundingdataset received thereafter (where n is any integer number greater than1).

FIG. 10A shows a flowchart illustrating an example process 1000 forwireless communication that supports sounding for RF sensing accordingto some implementations. In some implementations, the process 1000 maybe performed by a wireless communication device operating as or withinan AP, such as one of the APs 102 or 602 described above with referenceto FIGS. 1 and 6A respectively. In some other implementations, theprocess 1000 may be performed by a wireless communication deviceoperating as or within a network node, such as one of the STAs 104 or604 described above with reference to FIGS. 1 and 6B, respectively.

In some implementations, the process 1000 begins in block 1002 withreceiving a sounding dataset, over a wireless channel, from atransmitting device, where the sounding dataset includes informationcarried in one or more training fields configured for channel estimationand sounding control information indicating a configuration of thetransmitting device. In some implementations, the sounding controlinformation may include a sequence number indicating the configurationof the transmitting device. In some implementations, the soundingcontrol information may include timing information or informationindicating one or more transmission parameters associated with thetransmission of the sounding dataset by the transmitting device. Inblock 1004, the process 1000 proceeds with acquiring CSI for thewireless channel based on the received sounding dataset. In block 1006,the process 1000 proceeds with selectively transmitting a channel reportto the transmitting device based at least in part on the CSI and thesounding control information.

In some implementations, the channel report may include a sequencenumber indicating a configuration of the wireless communication device.In some implementations, the channel report may include timinginformation or information indicating one or more reception parametersassociated with the reception of the sounding dataset. In someimplementations, the operation for selectively transmitting a channelreport, in block 1006, may include obtaining an indication that an RSSIassociated with the sounding dataset is below an RSSI threshold, whereno channel report is transmitted to the transmitting device based on theindication that the RSSI is below the RSSI threshold.

FIG. 10B shows a flowchart illustrating an example process 1010 forwireless communication that supports sounding for RF sensing accordingto some implementations. In some implementations, the process 1010 maybe performed by a wireless communication device operating as or withinan AP, such as one of the APs 102 or 602 described above with referenceto FIGS. 1 and 6A respectively. In some other implementations, theprocess 1010 may be performed by a wireless communication deviceoperating as or within a network node, such as one of the STAs 104 or604 described above with reference to FIGS. 1 and 6B, respectively.

With reference for example to FIG. 10A, the process 1010 may beperformed prior to the operation for selectively transmitting a channelreport in block 1006 of the process 1000. In some implementations, theprocess 1010 begins in block 1012 with acquiring CSI for a referencechannel. In block 1014, the process 1010 proceeds with obtaining anindication of a difference between the CSI for the wireless channel andthe CSI for the reference channel. In some implementations, the channelreport may include the indication of the difference in CSI. In someimplementations, the operation for selectively transmitting a channelreport, in block 1006, may include comparing the difference in CSI to aCSI difference threshold, where no channel report is transmitted to thetransmitting device based on the difference in CSI being below the CSIdifference threshold.

FIG. 11A shows a flowchart illustrating an example process 1100 forwireless communication that supports sounding for RF sensing accordingto some implementations. In some implementations, the process 1100 maybe performed by a wireless communication device operating as or withinan AP, such as one of the APs 102 or 602 described above with referenceto FIGS. 1 and 6A respectively. In some other implementations, theprocess 1100 may be performed by a wireless communication deviceoperating as or within a network node, such as one of the STAs 104 or604 described above with reference to FIGS. 1 and 6B, respectively.

In some implementations, the process 1100 begins in block 1102 withgenerating sounding control information based, at least in part, on aconfiguration of the wireless communication device. In someimplementations, the sounding control information may include a sequencenumber indicating the configuration of the wireless communicationdevice. In some implementations, the sounding control information mayinclude timing information or one or more transmission parametersassociated with the transmission of the sounding dataset. In block 1104,the process 1100 proceeds with transmitting a sounding dataset, over awireless channel, to a receiving device, where the sounding dataincludes the sounding control information and information carried in oneor more training fields configured for channel estimation.

FIG. 11B shows a flowchart illustrating an example process 1110 forwireless communication that supports sounding for RF sensing accordingto some implementations. In some implementations, the process 1110 maybe performed by a wireless communication device operating as or withinan AP, such as one of the APs 102 or 602 described above with referenceto FIGS. 1 and 6A respectively. In some other implementations, theprocess 1110 may be performed by a wireless communication deviceoperating as or within a network node, such as one of the STAs 104 or604 described above with reference to FIGS. 1 and 6B, respectively.

With reference for example to FIG. 11A, the process 1110 may beperformed after the operation for transmitting the sounding dataset inblock 1104 of the process 1100. In some implementations, the process1110 begins in block 1112 with receiving a channel report from thereceiving device responsive to the transmission of the sounding dataset,where the channel report includes CSI for the wireless channel. In someimplementations, the channel report may include a subset of the soundingcontrol information. In some implementations, the channel report mayinclude a sequence number indicating a configuration of the receivingdevice. In some implementations, the channel report may include timinginformation or information indicating one or more reception parametersassociated with a reception of the sounding dataset by the receivingdevice. In block 1114, the process 1110 proceeds with sensing objects ina vicinity of the wireless communication device based on the receivedchannel report.

In some implementations, the channel report may further indicate adifference in CSI between the wireless channel and a reference channel.In some implementations, the sounding control information may identifythe reference channel. In some implementations, the sounding controlinformation may identify the wireless channel as a reference channel forfuture channel reports.

FIG. 12 shows a block diagram of an example wireless communicationdevice 1200 for use in wireless communication according to someimplementations. In some implementations, the wireless communicationdevice 1200 may be configured to perform any of the processes 1000 or1010 described above with reference to FIGS. 10A and 10B, respectively.In some implementations, the wireless communication device 1200 can bean example implementation of the wireless communication device 500described above with reference to FIG. 5. For example, the wirelesscommunication device 1200 can be a chip, SoC, chipset, package or devicethat includes at least one processor and at least one modem (forexample, a Wi-Fi (IEEE 802.11) modem or a cellular modem). In someimplementations, the wireless communication device 1200 can be a devicefor use in an AP, such as one of the APs 102 and 602 described abovewith reference to FIGS. 1 and 6A, respectively. In some otherimplementations, the wireless communication device 1200 can be a devicefor use in a STA, such as one of the STAs 104 and 604 described abovewith reference to FIGS. 1 and 6B, respectively.

The wireless communication device 1200 includes a module for receivingsounding data 1202, a module for acquiring CSI 1204, and a module fortransmitting channel reports 1206. Portions of one or more of themodules 1202, 1204, and 1206 may be implemented at least in part inhardware or firmware. In some implementations, at least some of themodules 1202, 1204, and 1206 are implemented at least in part assoftware stored in a memory (such as the memory 508). For example,portions of one or more of the modules 1202, 1204, and 1206 can beimplemented as non-transitory instructions (or “code”) executable by aprocessor (such as the processor 506) to perform the functions oroperations of the respective module.

The module for receiving sounding data 1202 is configured to receive asounding dataset, over a wireless channel, from a transmitting device,where the sounding dataset includes information carried in one or moretraining fields configured for channel estimation and sounding controlinformation indicating a configuration of the transmitting device. Themodule for acquiring CSI 1204 is configured to acquire CSI for thewireless channel based on the received sounding dataset. The module fortransmitting channel reports 1206 is configured to selectively transmita channel report to the transmitting device based at least in part onthe CSI and the sounding control information.

FIG. 13 shows a block diagram of an example wireless communicationdevice 1300 for use in wireless communication according to someimplementations. In some implementations, the wireless communicationdevice 1300 may be configured to perform any of the processes 1100 or1110 described above with reference to FIGS. 11A and 11B, respectively.In some implementations, the wireless communication device 1300 can bean example implementation of the wireless communication device 500described above with reference to FIG. 5. For example, the wirelesscommunication device 1300 can be a chip, SoC, chipset, package or devicethat includes at least one processor and at least one modem (forexample, a Wi-Fi (IEEE 802.11) modem or a cellular modem). In someimplementations, the wireless communication device 1300 can be a devicefor use in a STA, such as one of the STAs 104 and 604 described abovewith reference to FIGS. 1 and 6B, respectively. In some otherimplementations, the wireless communication device 1300 can be a devicefor use in an AP, such as one of the APs 102 and 602 described abovewith reference to FIGS. 1 and 6A, respectively.

The wireless communication device 1300 includes a module for generatingsounding control information 1302 and a module for transmitting soundingdata 1304. Portions of one or more of the modules 1302 and 1304 may beimplemented at least in part in hardware or firmware. In someimplementations, at least some of the modules 1302 and 1304 areimplemented at least in part as software stored in a memory (such as thememory 508). For example, portions of one or more of the modules 1302and 1304 can be implemented as non-transitory instructions (or “code”)executable by a processor (such as the processor 506) to perform thefunctions or operations of the respective module.

The module for generating sounding control information 1302 isconfigured to generate sounding control information based, at least inpart, on a configuration of the wireless communication device. Themodule for transmitting sounding data 1304 is configured to transmit asounding dataset, over a wireless channel, to a receiving device, wherethe sounding dataset includes the sounding control information andinformation carried in one or more training fields configured forchannel estimation.

As used herein, a phrase referring to “at least one of” or “one or moreof” a list of items refers to any combination of those items, includingsingle members. For example, “at least one of: a, b, or c” is intendedto cover the possibilities of: a only, b only, c only, a combination ofa and b, a combination of a and c, a combination of b and c, and acombination of a and b and c.

The various illustrative components, logic, logical blocks, modules,circuits, operations and algorithm processes described in connectionwith the implementations disclosed herein may be implemented aselectronic hardware, firmware, software, or combinations of hardware,firmware or software, including the structures disclosed in thisspecification and the structural equivalents thereof. Theinterchangeability of hardware, firmware and software has been describedgenerally, in terms of functionality, and illustrated in the variousillustrative components, blocks, modules, circuits and processesdescribed above. Whether such functionality is implemented in hardware,firmware or software depends upon the particular application and designconstraints imposed on the overall system.

Implementation examples are described in the following numbered clauses:

-   -   1. A method for wireless communication performed by a wireless        communication device, including:    -   receiving a sounding dataset, over a wireless channel, from a        transmitting device, the sounding dataset including information        carried in one or more training fields configured for channel        estimation and sounding control information indicating a        configuration of the transmitting device;    -   acquiring channel state information (CSI) for the wireless        channel based on the received sounding dataset; and    -   selectively transmitting a channel report to the transmitting        device based at least in part on the CSI and the sounding        control information.    -   2. The method of clause 1, wherein the sounding control        information includes a sequence number indicating the        configuration of the transmitting device.    -   3. The method of any of clauses 1 or 2, wherein the sounding        control information includes timing information or information        indicating one or more transmission parameters associated with a        transmission of the sounding dataset by the transmitting device.    -   4. The method of any of clauses 1-3, wherein the channel report        includes a subset of the sounding control information.    -   5. The method of any of clauses 1-4, wherein the channel report        includes a sequence number indicating a configuration of the        wireless communication device.    -   6. The method of any of clauses 1-5, wherein the channel report        includes timing information or information indicating one or        more reception parameters associated with the reception of the        sounding dataset.    -   7. The method of any of clauses 1-6, wherein the selective        transmitting of a channel report includes:    -   obtaining an indication that a received signal strength        indication (RSSI) associated with the sounding dataset is below        an RSSI threshold, no channel report being transmitted to the        transmitting device based on the indication that the RSSI is        below the RSSI threshold.    -   8. The method of any of clauses 1-6, further including:    -   acquiring CSI for a reference channel; and    -   obtaining an indication of a difference between the CSI for the        wireless channel and the CSI for the reference channel.    -   9. The method of any of clauses 1-6 or 8, wherein the channel        report includes the indication of the difference in CSI.    -   10. The method of any of clauses 1-6, or 8, wherein the        selective transmitting of a channel report comprises:    -   comparing the difference in CSI to a CSI difference threshold,        no channel report being transmitted to the transmitting device        based on the difference in CSI being below the CSI difference        threshold.    -   11. A wireless communication device including:    -   at least one modem;    -   at least one processor communicatively coupled with the at least        one modem; and    -   at least one memory communicatively coupled with the at least        one processor and storing processor-readable code that, when        executed by the at least one processor in conjunction with the        at least one modem, is configured to perform the method of any        one or more of clauses 1-10.    -   12. A method for wireless communication performed by a wireless        communication device, including:    -   generating sounding control information based, at least in part,        on a configuration of the wireless communication device; and    -   transmitting a sounding dataset, over a wireless channel, to a        receiving device, the sounding dataset including the sounding        control information and information carried in one or more        training fields configured for channel estimation.    -   13. The method of clause 12, wherein the sounding control        information includes a sequence number indicating the        configuration of the wireless communication device.    -   14. The method of any of clauses 12 or 13, wherein the sounding        control information includes timing information or one or more        transmission parameters associated with the transmission of the        sounding dataset.    -   15. The method of any of clauses 12-14, further including:    -   receiving a channel report from the receiving device responsive        to the transmission of the sounding dataset, the channel report        including channel station information (CSI) for the wireless        channel; and    -   sensing objects in a vicinity of the wireless communication        device based on the received channel report.    -   16. The method of any of clauses 12-15, wherein the channel        report includes a subset of the sounding control information.    -   17. The method of any of clauses 12-16, wherein the channel        report includes a sequence number indicating a configuration of        the receiving device.    -   18. The method of any of clauses 12-17, wherein the channel        report includes timing information or information indicating one        or more reception parameters associated with a reception of the        sounding dataset by the receiving device.    -   19. The method of any of clauses 12-18, wherein the channel        report indicates a difference in CSI between the wireless        channel and a reference channel.    -   20. The method of any of clauses 12-19, wherein the sounding        control information identifies the reference channel.    -   21. The method of any of clauses 12-20, wherein the sounding        control information identifies the wireless channel as a        reference channel for future channel reports.    -   22. A wireless communication device including:    -   at least one modem;    -   at least one processor communicatively coupled with the at least        one modem; and    -   at least one memory communicatively coupled with the at least        one processor and storing processor-readable code that, when        executed by the at least one processor in conjunction with the        at least one modem, is configured to perform the method of any        one or more of clauses 12-21.

Various modifications to the implementations described in thisdisclosure may be readily apparent to persons having ordinary skill inthe art, and the generic principles defined herein may be applied toother implementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

Additionally, various features that are described in this specificationin the context of separate implementations also can be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation also can beimplemented in multiple implementations separately or in any suitablesubcombination. As such, although features may be described above asacting in particular combinations, and even initially claimed as such,one or more features from a claimed combination can in some cases beexcised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flowchart or flow diagram. However, otheroperations that are not depicted can be incorporated in the exampleprocesses that are schematically illustrated. For example, one or moreadditional operations can be performed before, after, simultaneously, orbetween any of the illustrated operations. In some circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.

What is claimed is:
 1. A method for wireless communication performed bya wireless communication device, comprising: receiving a soundingdataset, over a wireless channel, from a transmitting device, thesounding dataset including information carried in one or more trainingfields configured for channel estimation and sounding controlinformation indicating a configuration of the transmitting device;acquiring channel state information (CSI) for the wireless channel basedon the received sounding dataset; and selectively transmitting a channelreport to the transmitting device based at least in part on the CSI andthe sounding control information.
 2. The method of claim 1, wherein thesounding control information includes a sequence number indicating theconfiguration of the transmitting device.
 3. The method of claim 1,wherein the sounding control information includes timing information orinformation indicating one or more transmission parameters associatedwith a transmission of the sounding dataset by the transmitting device.4. The method of claim 3, wherein the channel report includes a subsetof the sounding control information.
 5. The method of claim 1, whereinthe channel report includes a sequence number indicating a configurationof the wireless communication device.
 6. The method of claim 1, whereinthe channel report includes timing information or information indicatingone or more reception parameters associated with the reception of thesounding dataset.
 7. The method of claim 1, wherein the selectivetransmitting of a channel report comprises: obtaining an indication thata received signal strength indication (RSSI) associated with thesounding dataset is below an RSSI threshold, no channel report beingtransmitted to the transmitting device based on the indication that theRSSI is below the RSSI threshold.
 8. The method of claim 1, furthercomprising: acquiring CSI for a reference channel; and obtaining anindication of a difference between the CSI for the wireless channel andthe CSI for the reference channel.
 9. The method of claim 8, wherein thechannel report includes the indication of the difference in CSI.
 10. Themethod of claim 8, wherein the selective transmitting of a channelreport comprises: comparing the difference in CSI to a CSI differencethreshold, no channel report being transmitted to the transmittingdevice based on the difference in CSI being below the CSI differencethreshold.
 11. A wireless communication device comprising: at least onemodem; at least one processor communicatively coupled with the at leastone modem; and at least one memory communicatively coupled with the atleast one processor and storing processor-readable code that, whenexecuted by the at least one processor in conjunction with the at leastone modem, is configured to: receive a sounding dataset, over a wirelesschannel, from a transmitting device, the sounding dataset includinginformation carried in a training field of a sounding packet andsounding control information indicating a configuration of thetransmitting device; acquire channel state information (CSI) for thewireless channel based on the received sounding dataset; and selectivelytransmit a channel report to the transmitting device based at least inpart on the CSI and the sounding control information.
 12. The wirelesscommunication device of claim 11, wherein the selective transmitting ofa channel report comprises: obtaining an indication that a receivedsignal strength indication (RSSI) associated with the sounding datasetis below an RSSI threshold, no channel report being transmitted to thetransmitting device based on the indication that the RSSI is below theRSSI threshold.
 13. The wireless communication device of claim 11,wherein execution of the processor-readable code is further configuredto: acquire CSI for a reference channel; and obtain an indication of adifference between the CSI for the wireless channel and the CSI for thereference channel.
 14. The wireless communication device of claim 13,wherein the channel report includes the indication of the difference inCSI.
 15. The wireless communication device of claim 13, wherein theselective transmitting of a channel report comprises: comparing thedifference in CSI to a CSI difference threshold, no channel report beingtransmitted to the transmitting device based on the difference in CSIbeing below the CSI difference threshold.
 16. A method for wirelesscommunication performed by a wireless communication device, comprising:generating sounding control information based, at least in part, on aconfiguration of the wireless communication device; and transmitting asounding dataset, over a wireless channel, to a receiving device, thesounding dataset including the sounding control information andinformation carried in one or more training fields configured forchannel estimation.
 17. The method of claim 16, wherein the soundingcontrol information includes a sequence number indicating theconfiguration of the wireless communication device.
 18. The method ofclaim 16, wherein the sounding control information includes timinginformation or one or more transmission parameters associated with thetransmission of the sounding dataset.
 19. The method of claim 16,further comprising: receiving a channel report from the receiving deviceresponsive to the transmission of the sounding dataset, the channelreport including channel station information (CSI) for the wirelesschannel; and sensing objects in a vicinity of the wireless communicationdevice based on the received channel report.
 20. The method of claim 19,wherein the channel report includes a subset of the sounding controlinformation.
 21. The method of claim 19, wherein the channel reportincludes a sequence number indicating a configuration of the receivingdevice.
 22. The method of claim 19, wherein the channel report includestiming information or information indicating one or more receptionparameters associated with a reception of the sounding dataset by thereceiving device.
 23. The method of claim 19, wherein the channel reportindicates a difference in CSI between the wireless channel and areference channel.
 24. The method of claim 23, wherein the soundingcontrol information identifies the reference channel.
 25. The method ofclaim 23, wherein the sounding control information identifies thewireless channel as a reference channel for future channel reports. 26.A wireless communication device comprising: at least one modem; at leastone processor communicatively coupled with the at least one modem; andat least one memory communicatively coupled with the at least oneprocessor and storing processor-readable code that, when executed by theat least one processor in conjunction with the at least one modem, isconfigured to: generate sounding control information based, at least inpart, on a configuration of the wireless communication device; andtransmit a sounding dataset, over a wireless channel, to a receivingdevice, the sounding dataset including the sounding control informationand information carried in one or more training fields configured forchannel estimation.
 27. The wireless communication device of claim 26,wherein execution of the processor-readable code is further configuredto: receive a channel report from the receiving device responsive to thetransmission of the sounding dataset, the channel report includingchannel station information (CSI) for the wireless channel; and senseobjects in a vicinity of the wireless communication device based on thereceived channel report.
 28. The wireless communication device of claim27, wherein the channel report indicates a difference in CSI between thewireless channel and a reference channel.
 29. The wireless communicationdevice of claim 28, wherein the sounding control information identifiesthe reference channel.
 30. The wireless communication device of claim28, wherein the sounding control information identifies the wirelesschannel as a reference channel for future channel reports.